title: Healthy Neonates Possess a CD56-Negative NK Cell Population with Reduced Anti-Viral Activity.
abstract: Neonatal Natural Killer (NK) cells show functional impairment and expansion of a CD56 negative population of uncertain significance.
  
  
  
  NK cells were isolated from cord blood and from adult donors. NK subpopulations were identified as positive or negative for the expression of CD56 and characterized for expression of granzyme B and surface markers by multi-parameter flow cytometry. Cell function was assessed by viral suppression and cytokine production using autologous lymphocytes infected with HIV. Activating (NKp30, NKp46) and inhibitory (Siglec-7) markers in healthy infants and adults were compared with viremic HIV-infected adults.
  
  
  
  Cord blood contained increased frequencies of CD56 negative (CD56neg) NK cells with reduced expression of granzyme B and reduced production of IFNγ and the CC-class chemokines RANTES, MIP1α and MIP1β upon stimulation. Both CD56pos and CD56neg NK subpopulations showed impaired viral suppression in cord blood, with impairment most marked in the CD56neg subset. CD56neg NK cells from cord blood and HIV-infected adults shared decreased inhibitory and activating receptor expression when compared with CD56pos cells.
  
  
  
  CD56neg NK cells are increased in number in normal infants and these effectors show reduced anti-viral activity. Like the expanded CD56neg population described in HIV-infected adults, these NK cells demonstrate functional impairments which may reflect inadequate development or activation.
authors.affiliation: Seattle Biomedical Research Institute, Seattle, Washington, United States of America.
authors.forename: Amanda
authors.initials: A
authors.lastname: Jacobson
authors.forename: Frank
authors.initials: F
authors.lastname: Bell
authors.forename: Nicholas
authors.initials: N
authors.lastname: Lejarcegui
authors.forename: Caroline
authors.initials: C
authors.lastname: Mitchell
authors.forename: Lisa
authors.initials: L
authors.lastname: Frenkel
authors.forename: Helen
authors.initials: H
authors.lastname: Horton
mesh_terms: D000328:Adult; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000637:transplantation; D019002:CD56 Antigen / Q000378:metabolism*; D018925:Chemokines / Q000032:analysis; D016207:Cytokines / Q000032:analysis; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism; D053804:Granzymes / Q000378:metabolism; D006678:HIV / Q000502:physiology; D015658:HIV Infections / Q000276:immunology / Q000628:therapy; D006801:Humans; D007118:Immunoassay; D007371:Interferon-gamma / Q000378:metabolism; D007694:Killer Cells, Natural / Q000166:cytology* / Q000378:metabolism; D037102:Lectins / Q000378:metabolism; D055627:Natural Cytotoxicity Triggering Receptor 1 / Q000378:metabolism; D055628:Natural Cytotoxicity Triggering Receptor 3 / Q000378:metabolism; D010641:Phenotype; D014182:Transplantation, Autologous; D014779:Virus Replication
chemical_list: D015214:Antigens, Differentiation, Myelomonocytic; D019002:CD56 Antigen; D018925:Chemokines; D016207:Cytokines; D037102:Lectins; C112260:NCR1 protein, human; C431710:NCR3 protein, human; D055627:Natural Cytotoxicity Triggering Receptor 1; D055628:Natural Cytotoxicity Triggering Receptor 3; C402206:SIGLEC7 protein, human; D007371:Interferon-gamma; D053804:Granzymes